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As approved by the Board of Directors of
Phio Pharmaceuticals Corp. (the “Company”), on December 19, 2018, the Company and Geert Cauwenbergh, Dr. Med.
Sc., the Company’s Chief Executive Officer (the “CEO”), agreed to extend by two months (the “Extension
Agreement”) the CEO’s prior irrevocable election (the “Election”) to receive 50% of his base
salary and cash bonuses, if any (collectively, the “Compensation”), in the form of unvested, restricted shares
of the Company’s common stock (“RSUs”). The description of the Non-Plan Stock Compensation Election and
Terms and Conditions, pursuant to which the Election was made (the “Terms and Conditions”), was described in
Item 5.02 to the Company’s September 4, 2018, Current Report on Form 8-K and is incorporated herein by reference (including
the full text of the Terms and Conditions filed therewith as Exhibit 10.1).

Prior to the Extension Agreement, the Election
covered Compensation from September 15, 2018 through December 31, 2018 (the “Initial Period”) and all RSUs received
pursuant to the Election were to vest in full on January 1, 2019, subject to the CEO’s continued employment with the Company.
The Extension Agreement (i) extends the applicable period of the Election through February 28, 2019, and (ii) provides that all
RSUs granted pursuant to the Election shall vest on March 1, 2019, including those RSUs granted during the Initial Period. Other
than the aforementioned changes, the Terms and Conditions will continue to apply.

The preceding description is qualified in
its entirety by reference to the full text of the Extension Agreement, a copy of which is filed as Exhibit 10.1 to this Current
Report on Form 8-K and incorporated herein by reference.

Pursuant to the requirements of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

PHIO PHARMACEUTICALS CORP.

Date: December 21, 2018

By:

/s/ Geert Cauwenbergh

Geert Cauwenbergh, Dr. Med. Sc.

Chief Executive Officer

3

Exhibit 10.1

Amendment
No. 1

To

Non-Plan Stock Compensation
Election

and Terms and Conditions

Reference is made to that
certain election agreement (the “Election Agreement”) pursuant to which Phio Pharmaceuticals Corp., a Delaware
corporation (formerly known as RXi Pharmaceuticals Corporation, the “Company”) permitted Geert Cauwenbergh,
Dr. Med. Sc. (the “CEO”) to make an irrevocable election to receive Compensation for the period from September
15, 2018 through December 31, 2018 (the “Initial Period”) in the form of cash or restricted shares of Company
Common Stock. All capitalized but undefined words used herein shall have the meaning set forth in the Election Agreement.

WHEREAS, pursuant to the
Election Agreement, the CEO irrevocably elected to receive 50% of his Compensation in the form of a series of grants of unvested,
restricted shares (“RSUs”) of Common Stock (the “Election”); and

WHEREAS, all RSUs received
pursuant to a Stock Election vest in full on January 1, 2019 (the “Initial Vesting Date”).

In consideration of the
mutual agreements contained herein, the CEO and the Company hereto agree as follows:

1. The
Initial Period under the Election Agreement shall be extended by two months, such that the Election
will irrevocably apply to the
CEO’s Compensation through February 28, 2019 (the “Extension Period”).

2. The
Initial Vesting Date shall be delayed by two months, such that all RSUs received pursuant to a Stock Election, including during
the Initial Period, will vest in full on March 1, 2019 (the “New Vesting Date”).

3. Other
than providing for the Extension Period and the New Vesting Date, this amendment shall not alter any of the terms, obligations,
or rights contained in the Election Agreement.

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blank]

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Phio Pharmaceuticals
Corp.

By: /s/
Gerrit Dispersyn

Name
Gerrit Dispersyn

Title:
President & COO

By signing below, the CEO
agrees to the New Vesting Date and acknowledges he has made an irrevocable election to receive Compensation through the Extension
Period.